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I am trying openjpa and jpa. All I have is one entity class as corresponding table in the database. one of the attributes of the entity is username and corresponding row in the db table has varchar2(20). and in my main method what i tried to persist and instance of the entity with username longer than 20. All I am doing is 

em.getTransaction().begin();
em.persist(entity); //entity here is the instance with the username longer than 20
em.getTransaction().commit();

I tried this, hoping to get some other kind of exception, but I don't why I am getting optimisticklockexception.

I do not have any locking setting. I mean I am using default values for locking property.

Does anybody know what's happening here?

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1 回答 1

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不知道为什么会发生这种情况......我注意到 OptimisticLockException 可能会在奇怪的情况下被抛出......

向您的表和实体添加版本字段通常可以使 OpenJPA 更好地使用锁定...

在您的实体 bean 中添加以下内容（还将名为 VERSION 的列添加到您的表中）：

private Long version;
@Version
@Column(name="VERSION") 
public Long getVersion() {
    return version;
}
public void setVersion(Long version) {
    this.version = version;
}

希望这可以帮助...

于 2011-03-11T19:16:41.140 回答